Environmental Geology
- Gothenburg Northern Archipelago
The Nordre älv estuary is dominated by freshwater outflow, has little tidal influence and a large width to depth ratio. This properties of the estuary allows a halocline to form and salt- and freshwater mixing which is a unique environment that has high natural value (Göta Älvs Vattenvårdsförbund, 2015). The hydrological conditions of the Göta älv estuary is more changing than of the Nordre älv estuary. The Göta älv estuary is more affected by tides and ships entering the harbour which contributes to more turbulent conditions.
​
The Nordre älv and the Göta älv rivers are the main suppliers of pollutants to the Northern archipelago of Gothenburg. The sources of the pollutants differ for the two estuaries. The Göta älv is highly affected by urban and industrial sources of pollutants where as the Nordre älv is mainly affected by pollutions from agriculture. Further upstream both rivers congregate to form the main Göta älv which water quality is strongly affected by its source, the lake Vänern.
The archipelago of this study is located in the southwestern parts of Sweden outside the city of Gothenburg and it is a part of Västerhavet. The Gothenburg archipelago is devided into the northern and the southern parts. The northern archipelago is confined by the estuary of the river Göta Älv in the south and the estuary of the river Nordre Älv to the North.
​
The northern archipelago consists of many islands where the largest one is Hisingen which is one of the largest islands in sweden (SCB, 2014). Apart from Hisingen, four larger islands and some smaller islands are located in the archipelago. Even though Hisingen is an island it is only separated from the mainland by the the two rivers, Nordre Älv and Göta Älv. The shore along the Hisingen coastline is diverse with smaller and larger calm coves and more wind exposed cliffs and beaches. The fetch affecting the shoreline influences the energy levels and sedimentation processes of these areas.
Area description and environmental problems
Hisingen
Nordre älv esturay
Göta älv esturay
Industries in the area affecting the Göta älv esturay are car manufacturing, two larger oil refineries and old shipyards. There is a waste water treatment plant, Ryaverket, located in the estuary flowing out into the Göta Älv river. On Hisingen there are many large marinas which are specialised in shipping of crude oil, container gods, forestry and petrol/diesel/heating oil, mainly affecting the Göta älv estuary. There are also many smaller marinas along the shore and on the islands which affect Västerhavet directly.
(Göta Älvs Vattenvårdsförbund, 2015).
​
The Gothenburg harbour is the largest in Scandinavia and passing through is almost 30 % of the Swedish export. The Export is mainly steal and forestry products and the import is dominated by consumption goods arriving in containers. 11 thousand ships are arriving in the Gothenburg harbour every year and approximately 20 million tons of oil, 250 thousand cars, 800 thousand containers and 1,7 million passengers are passing through.
​
Photo: Ingrid Jillerö
The transport connections from the harbour to the inland is by train and with cargo trucks on the larger freeways, E20, E6 and E45. About 70 large cargo trains are daily trafficking the harbor and reaching the larger cities in Sweden and Norway.
( Gothenburg Harbour, 2013)
​
Eutrophication is affecting the water in the areas and nutrients (N and P) are transported to Västerhavet with the river water. The sources of the nutrients is in falling order from: agriculture, forestry and sewage plants/ personal sewage. (Göta Älvs Vattenvårdsförbund, 2015).
Map of major landuse and infrastructure in the Northern gothenburg Area
Environmental sketch of the system, Northern gothenburg Archipelago.